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2025 KTM 125 SX

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2025 KTM 125 SX

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  • Base Price: 8,999.00 GBP*

*inc VAT, delivery to dealer and PDI

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*inc VAT, delivery to dealer and PDI

SHOW MORE
There are very few sounds that can't be beaten. The crack of a soda can on a blistering hot day. The ping of the perfectly executed golf shot. And the scream of a 125 cc 2-stroke charging down a long straightaway. The 2025 KTM 125 SX takes its leads directly from the Factory Racing team and puts them to work like nothing else. Like the sound it makes, it cannot be beaten.

This motorcycle is designed, developed and produced in Austria.
  • PHO_BIKE_90_RE_MY25-KTM-125-SX-90-right-Studio_#SALL_#AEPI_#V1.png
    PHO_BIKE_90_LI_MY25-KTM-125-SX-90-left-Studio_#SALL_#AEPI_#V1.png
    PHO_BIKE_90_REVO_MY25-KTM-125-SX-90-front-right-Studio_#SALL_#AEPI_#V1.png
There are very few sounds that can't be beaten. The crack of a soda can on a blistering hot day. The ping of the perfectly executed golf shot. And the scream of a 125 cc 2-stroke charging down a long straightaway. The 2025 KTM 125 SX takes its leads directly from the Factory Racing team and puts them to work like nothing else. Like the sound it makes, it cannot be beaten.

This motorcycle is designed, developed and produced in Austria.
  1. Before The Gate
  2. Start Strong
  3. Calm Under Fire
  4. Hit The Big Stuff
  5. Maintaining Momentum
Before The Gate

01. Before The Gate

NO JETS - ONLY ROCKET SHIPS
NO JETS - ONLY ROCKET SHIPS

Electronic Fuel Injection

Pre-mix gets a remix across the 2-stroke KTM SX range, with Electronic Fuel Injection setting the standard. Now there's no more fiddly jetting setup pre-race, And thanks to the Keihin EFI and reed valve case design, you can be guaranteed of laying down optimal power at any altitude, all of the time.

CHUGGA CHUGGA, RING DING DING!
CHUGGA CHUGGA, RING DING DING!

Electric Start

Picture this; You're 7 laps into an absolute ripper of a race. You miss your line and end up stalling in a deep rut. But you don't sweat it. All you do is press the starter button and you blast off again to take the final flag. This is the reality on the 2025 KTM 125 SX. Thanks to a 12,8V 2 Ah lithium ion battery is placed under the rider's seat, a high-quality stator & pickup and super robust design, the only thing you'll be kicking - is ass.

CLICK INTO ACTION
CLICK INTO ACTION

Easy Suspension Adjustment

As always, the suspension boasts an easy tool-free setup at both ends, ensuring you chase down the podium in total control. On the rear, a hand-adjustable dual compression control allows riders to adjust high- and low-speed settings in a matter of seconds. The forks on the front end are also easily adjusted thanks to hand-adjustable clickers on the bottom of the fork shoe and top cap.

Before The Gate
NO JETS - ONLY ROCKET SHIPS
NO JETS - ONLY ROCKET SHIPS

Electronic Fuel Injection

Pre-mix gets a remix across the 2-stroke KTM SX range, with Electronic Fuel Injection setting the standard. Now there's no more fiddly jetting setup pre-race, And thanks to the Keihin EFI and reed valve case design, you can be guaranteed of laying down optimal power at any altitude, all of the time.
NO JETS - ONLY ROCKET SHIPS
Before The Gate
CHUGGA CHUGGA, RING DING DING!
CHUGGA CHUGGA, RING DING DING!

Electric Start

Picture this; You're 7 laps into an absolute ripper of a race. You miss your line and end up stalling in a deep rut. But you don't sweat it. All you do is press the starter button and you blast off again to take the final flag. This is the reality on the 2025 KTM 125 SX. Thanks to a 12,8V 2 Ah lithium ion battery is placed under the rider's seat, a high-quality stator & pickup and super robust design, the only thing you'll be kicking - is ass.
CHUGGA CHUGGA, RING DING DING!
Before The Gate
CLICK INTO ACTION
CLICK INTO ACTION

Easy Suspension Adjustment

As always, the suspension boasts an easy tool-free setup at both ends, ensuring you chase down the podium in total control. On the rear, a hand-adjustable dual compression control allows riders to adjust high- and low-speed settings in a matter of seconds. The forks on the front end are also easily adjusted thanks to hand-adjustable clickers on the bottom of the fork shoe and top cap.
CLICK INTO ACTION
Start Strong

02. Start Strong

Factory Performance Kit

Give your KTM 125 SX a more bite with a 125 Factory Performance Kit. Comprising of upgraded engine parts, a Factory expansion chamber, and special engine mapping, it provides a 2.5 hp increase while saving 15% of weight over the standard exhaust parts.

Available fall of 2024

SMOOTHER POWER DELIVERY
SMOOTHER POWER DELIVERY

EFI + Power Valve

With EFI comes great rideability. Along with the electronic fuel injection and a power valve on the KTM 125 SX, allowing for more usable power throughout the rev range. Smoother power means better traction. Better traction means holeshot heaven!

UNMATCHED PERFORMANCE
UNMATCHED PERFORMANCE

Performance

Designed to churn out torque the 2025 KTM 125 SX is set to continue its dominance in its class with unrelenting forward momentum. With an overall engine weight of only 17.86 kg and impressive horsepower figures, this lightweight powerplant retains its typical high-revving character, while laying down the grunt where it matters most.

PICK YOUR POWER
PICK YOUR POWER

Selectable Maps

Once again slicing into the 125 cc class with the leading edge of technology, the 2025 KTM 125 SX features a map select switch allowing the racer to switch between 2 engine maps. The White Map - or Map 1 - provides a linear, predictable power delivery ideally suited to attack hard-packed dirt with a leaner air-fuel mixture. Alternatively, the Green Map - Mapping 2 - is tuned for loose, thick sandy conditions with a richer mix.

Start Strong

Factory Performance Kit

Give your KTM 125 SX a more bite with a 125 Factory Performance Kit. Comprising of upgraded engine parts, a Factory expansion chamber, and special engine mapping, it provides a 2.5 hp increase while saving 15% of weight over the standard exhaust parts.

Available fall of 2024
Start Strong
SMOOTHER POWER DELIVERY
SMOOTHER POWER DELIVERY

EFI + Power Valve

With EFI comes great rideability. Along with the electronic fuel injection and a power valve on the KTM 125 SX, allowing for more usable power throughout the rev range. Smoother power means better traction. Better traction means holeshot heaven!
SMOOTHER POWER DELIVERY
Start Strong
UNMATCHED PERFORMANCE
UNMATCHED PERFORMANCE

Performance

Designed to churn out torque the 2025 KTM 125 SX is set to continue its dominance in its class with unrelenting forward momentum. With an overall engine weight of only 17.86 kg and impressive horsepower figures, this lightweight powerplant retains its typical high-revving character, while laying down the grunt where it matters most.
UNMATCHED PERFORMANCE
Start Strong
PICK YOUR POWER
PICK YOUR POWER

Selectable Maps

Once again slicing into the 125 cc class with the leading edge of technology, the 2025 KTM 125 SX features a map select switch allowing the racer to switch between 2 engine maps. The White Map - or Map 1 - provides a linear, predictable power delivery ideally suited to attack hard-packed dirt with a leaner air-fuel mixture. Alternatively, the Green Map - Mapping 2 - is tuned for loose, thick sandy conditions with a richer mix.
PICK YOUR POWER
Calm Under Fire

03. Calm Under Fire

SLEEKER FOR YOU TO SCRUB CLEANER
SLEEKER FOR YOU TO SCRUB CLEANER

Absolute Control

Get ready for a full-on berm assault. The 2025 KTM SX and SX-F machines have received major frame updates directly from Factory Racing efforts. For starters, the frame area around the rear shock mount has been updated and made more streamlined, with new engine mounts and cut-outs for improved chassis flex. The front area of the frame is also updated. with a different wall thickness than the previous model year, with renewed engine mounts. This adds up to a 300g weight saving and improved flex for better cornering.

FLUID RIDER MOTION
FLUID RIDER MOTION

Ergonomics

Upgraded tank shrouds using bi-compound plastics channel air towards the radiators more efficiently, while a new fuel tank roll, makes for a tighter, more secure fitment, reducing the chance of frame scrubbing and dramatically improving durability. All this works alongside the specially-developed rider triangle, to provide unmatched knee contact and gripping surfaces - especially when standing on the pegs.

HARNESSING GRAVITY
HARNESSING GRAVITY

Mass Centralization

With a major emphasis placed on mass centralization, the 2025 KTM 125 SX engine is designed to centralize rotating mass for optimal operation with the chassis. This results in a lighter, more agile handling feeling.

Calm Under Fire
SLEEKER FOR YOU TO SCRUB CLEANER
SLEEKER FOR YOU TO SCRUB CLEANER

Absolute Control

Get ready for a full-on berm assault. The 2025 KTM SX and SX-F machines have received major frame updates directly from Factory Racing efforts. For starters, the frame area around the rear shock mount has been updated and made more streamlined, with new engine mounts and cut-outs for improved chassis flex. The front area of the frame is also updated. with a different wall thickness than the previous model year, with renewed engine mounts. This adds up to a 300g weight saving and improved flex for better cornering.
SLEEKER FOR YOU TO SCRUB CLEANER
Calm Under Fire
FLUID RIDER MOTION
FLUID RIDER MOTION

Ergonomics

Upgraded tank shrouds using bi-compound plastics channel air towards the radiators more efficiently, while a new fuel tank roll, makes for a tighter, more secure fitment, reducing the chance of frame scrubbing and dramatically improving durability. All this works alongside the specially-developed rider triangle, to provide unmatched knee contact and gripping surfaces - especially when standing on the pegs.
FLUID RIDER MOTION
Calm Under Fire
HARNESSING GRAVITY
HARNESSING GRAVITY

Mass Centralization

With a major emphasis placed on mass centralization, the 2025 KTM 125 SX engine is designed to centralize rotating mass for optimal operation with the chassis. This results in a lighter, more agile handling feeling.
HARNESSING GRAVITY
Hit The Big Stuff

04. Hit The Big Stuff

Updated Suspension Settings

For 2025, the KTM SX and SX-F range has given the WP XACT AER fork and WP XACT rear shock an update. This means you'll be lining up at the setting gate with re-tuned settings, reduced weight, improved weight distribution, and an increase in overall response.

UNFLAPPABLE FRONT END
UNFLAPPABLE FRONT END

WP XACT Fork

Let's get the technical parts out of the way first; the 48 mm WP XACT AER forks fitted to the 2025 KTM SX and SX-F line-up features a capsulated air spring and pressurized oil chamber for progressive and consistent damping, while oil and air bypasses reduce pressure peaks. In combination with the mid-valve damping system, all this provides exceptional feedback and rider comfort. The fork also boasts new settings, which not only compliment the updated frame and rear linkage, but ensures stellar performance at all levels. Speaking of settings, these are easily adjusted via a single air pressure pre-load valve, as well as easy-access click adjusters for compression and rebound. Additionally, the air pump needed to adjust the fork's air pressure is provided as standard in the buy-pack.

WP XACT SHOCK

Keeping things in check at the rear, the WP XACT rear shock has also undergone some changes for 2025 using settings directly from the KTM Factory Racing Teams The improved frame and shock geometry mean more ground clearance at the linkage, making it less susceptible to bottoming out. While we're on the topic, smaller diameter linkage bolts save weight, while new linkage seals refine rear shock response and advanced damping characteristics.

RACING ON RAILS
RACING ON RAILS

Stability

An upgraded rear brake pedal finds its way onto the 2025 KTM Motocross range, adding additional stiffness, bending resistance and braking feel to the overall package. At the other end, a forged steering head connection and CNC-milled triple clamps, make for the perfect alignment of the fork tubes. This precise geometry of the fork clamps ensures highly responsive and smooth fork action – not to mention unwavering stability when charging across ruts and onto the podium.

Tires

Getting power hooked into the dirt is a tough job. However, hours of research and testing have led the 2025 KTM Motocross range to the Dunlop GEOMAX MX34. Providing unmatched stability and control at the highest level, these rubber hoops feature a new carcass and rubber compound that improves damping and absorption, maintaining performance up to 30% longer. New Progressive Cornering Block Technology also improves grip in the berms, while a new rear pattern with 11% taller and 44% wider center block for increased traction and control everywhere else. Lastly, this unique block arrangement works to dispel mud buildup, ensuring traction in even the muddiest of track conditions.

Hit The Big Stuff

Updated Suspension Settings

For 2025, the KTM SX and SX-F range has given the WP XACT AER fork and WP XACT rear shock an update. This means you'll be lining up at the setting gate with re-tuned settings, reduced weight, improved weight distribution, and an increase in overall response.
Hit The Big Stuff
UNFLAPPABLE FRONT END
UNFLAPPABLE FRONT END

WP XACT Fork

Let's get the technical parts out of the way first; the 48 mm WP XACT AER forks fitted to the 2025 KTM SX and SX-F line-up features a capsulated air spring and pressurized oil chamber for progressive and consistent damping, while oil and air bypasses reduce pressure peaks. In combination with the mid-valve damping system, all this provides exceptional feedback and rider comfort. The fork also boasts new settings, which not only compliment the updated frame and rear linkage, but ensures stellar performance at all levels. Speaking of settings, these are easily adjusted via a single air pressure pre-load valve, as well as easy-access click adjusters for compression and rebound. Additionally, the air pump needed to adjust the fork's air pressure is provided as standard in the buy-pack.
UNFLAPPABLE FRONT END
Hit The Big Stuff

WP XACT SHOCK

Keeping things in check at the rear, the WP XACT rear shock has also undergone some changes for 2025 using settings directly from the KTM Factory Racing Teams The improved frame and shock geometry mean more ground clearance at the linkage, making it less susceptible to bottoming out. While we're on the topic, smaller diameter linkage bolts save weight, while new linkage seals refine rear shock response and advanced damping characteristics.
Hit The Big Stuff
RACING ON RAILS
RACING ON RAILS

Stability

An upgraded rear brake pedal finds its way onto the 2025 KTM Motocross range, adding additional stiffness, bending resistance and braking feel to the overall package. At the other end, a forged steering head connection and CNC-milled triple clamps, make for the perfect alignment of the fork tubes. This precise geometry of the fork clamps ensures highly responsive and smooth fork action – not to mention unwavering stability when charging across ruts and onto the podium.
RACING ON RAILS
Hit The Big Stuff

Tires

Getting power hooked into the dirt is a tough job. However, hours of research and testing have led the 2025 KTM Motocross range to the Dunlop GEOMAX MX34. Providing unmatched stability and control at the highest level, these rubber hoops feature a new carcass and rubber compound that improves damping and absorption, maintaining performance up to 30% longer. New Progressive Cornering Block Technology also improves grip in the berms, while a new rear pattern with 11% taller and 44% wider center block for increased traction and control everywhere else. Lastly, this unique block arrangement works to dispel mud buildup, ensuring traction in even the muddiest of track conditions.

05. Maintaining Momentum

PRECISE, LAP AFTER LAP
PRECISE, LAP AFTER LAP

Consistency

A new chain guide and chain guard result in improved durability and minimize the chances of hooking on external objects - especially in extremely muddy conditions while reducing dirt build-up around the swingarm and rear sprocket.

UNOBTRUSIVE IMPACT
UNOBTRUSIVE IMPACT

Energy absorption

Besides the expertly crafted, hydro-formed, laser-cut, and robot-welded frame being engineered to provide exceptional rider feedback and straight-line stability, it consists of specifically calculated parameters of longitudinal and torsional flex. This means the frame acts as a "shock absorber" of sorts, making for a less harsh ride, resulting in less rider fatigue over many hard laps.

NOTHING TO HOLD YOU BACK
NOTHING TO HOLD YOU BACK

Ground clearance

No one enjoys a bad hook-up. Good thing, then that the shock absorber geometry on the 2025 KTM 250 SX improves ground clearance of the linkage, with the topology-optimized die-cast footpegs being less susceptible to hooking on deep ruts, and take-offs when scrubbing.

PRECISE, LAP AFTER LAP
PRECISE, LAP AFTER LAP

Consistency

A new chain guide and chain guard result in improved durability and minimize the chances of hooking on external objects - especially in extremely muddy conditions while reducing dirt build-up around the swingarm and rear sprocket.
PRECISE, LAP AFTER LAP
UNOBTRUSIVE IMPACT
UNOBTRUSIVE IMPACT

Energy absorption

Besides the expertly crafted, hydro-formed, laser-cut, and robot-welded frame being engineered to provide exceptional rider feedback and straight-line stability, it consists of specifically calculated parameters of longitudinal and torsional flex. This means the frame acts as a "shock absorber" of sorts, making for a less harsh ride, resulting in less rider fatigue over many hard laps.
UNOBTRUSIVE IMPACT
NOTHING TO HOLD YOU BACK
NOTHING TO HOLD YOU BACK

Ground clearance

No one enjoys a bad hook-up. Good thing, then that the shock absorber geometry on the 2025 KTM 250 SX improves ground clearance of the linkage, with the topology-optimized die-cast footpegs being less susceptible to hooking on deep ruts, and take-offs when scrubbing.
NOTHING TO HOLD YOU BACK

Technical Details

Engine

  • Transmission 6-speed
  • Starter Electric starter
  • Stroke 54.5 mm
  • Bore 54 mm
  • Clutch Wet multi-disc DS clutch, Brembo hydraulics
  • Displacement 124.8 cm³
  • EMS Vitesco Technologies EMS
  • Design 1-cylinder, 2-stroke engine
  • Fuel-mixture generation Keihin EFI, throttle body 39 mm

Chassis

  • Weight (without fuel) 92.4 kg
  • Tank capacity (approx.) 7.2 l
  • Wheelbase 1493 mm
  • Front brake disc diameter 260 mm
  • Rear brake disc diameter 220 mm
  • Front brake Disc brake
  • Rear brake Disc brake
  • Chain 520, Non-sealed
  • Frame design Central double-cradle-type 25CrMo4 steel
  • Front suspension WP XACT-USD (AER), Ø 48 mm
  • Ground clearance 359 mm
  • Handlebar Neken, aluminium Ø 28/22 mm
  • Rear suspension WP XACT Monoshock with linkage
  • Seat height 958 mm
  • Silencer Aluminium
  • Steering head angle 63.9 °
  • Rear subframe design Aluminum-reinforced polyamide
  • Suspension travel (front) 310 mm
  • Suspension travel (rear) 300 mm
  • Wheels Spoked wheels with aluminium rims